Billy's conclusions are just about right, and it is indeed sick for any parents to want such a thing. The blather about "culture" is just another manifestation of the cancerous moral and cultural relativism and aversion to judgement that allows for much more horrific things than this.
But what about the child? In the outrage a few years ago, the implication seemed to center on the damage done to the child by this choice, and Billy is not entirely clear on whether this factors into his outrage as well. But the truth is that the child is not damaged or diminshed in any way, and this is important to remember.
The specific child that results from this choice (assuming no actual genetic manipulation) could not have been born any other way. The choice here is not for this child to be born either deaf or hearing, but for this deaf child to be born or not. And unless you subscribe to the belief that it is possible to be harmed by being brought into existence, that anyone could be better off if they were never born, then the only conclusion is that this choice is an unmitigated good for this particular child.
(Note that there was some mention of the parents in such cases whitholding corrective measures for the child once born, and I could make an argument that this aspect of it is child abuse)
For the "normal" baby that might otherwise have been born, it's not such a great outcome. And for the parents who prefer crippled children to whole ones, (and the society that produces such people), well, they are damaged almost beyond repair. It's they I feel outrage for.
The child will have an uphill battle for a decent life - in part because of his disability, but mostly because he will be brought up by parents who see him as some kind of trophy, or worse, a living political statement - but for him the opportunity to live at all is the best thing that ever will happen to him.